Anode for magnesium primary cells



, PatentedApr. 26, 1960 alkaline-earth metal, or ammonium bromide electrolyte, an anode liner and a carbon current collector. The pres- 2,934,'583 ent inventionspecifically relates to an impgoivement in the anode of such a cell whereby the delay action is ANODE FOR MAGNESIUM PRIMARY CELLS 6 substantially reduced. Provision of such an anode is John A. Stevens, Midland, Micln, assignor to The Dow accomplished by providing a magnesium alloy containing Chemical Company, Midland, Mich., a corporation of from 0.03 to 1.7 percent indium, preferably from 0.1 Delaware to 0.2 percent indium. The indium is added in conv ,ventional alloyin techniques to the alloy melt and in No Drawmg siiir l i rfi i irr igi 1958 a conventional riranner, theresulting material settled, poured, pickled, extruded, rolled, or cast to form the 6 Claimsdesired style and shape of anode. Various of the wellknown magnesium anodes are improved by the addition of indium thereto. Representative alloy materials which This invention relates to an improved anode for use 15 are Suitable are those magnesium-base alloys containing ina p y magnesium battery cell whereby thenormai at least 80 percent, and preferably 90 percent magdeieyed action usually resulting from the employment nesi-um, containing from 1 to 12 percent aluminum, from of such a battery cell is decreased. 0.0 to 3.0 percent zinc, from 0.0 to 0.5 percent calcium, t has been Well established that P y Cells utilizing the balance being commercial magnesium containing not "magnesium as the anode, manganese dioxide mixed with over 0.005 percent iron, not over 0.002 percent nickel, carbon as the cathode, and a bromide of an alkali metal, d t over 6 percent manganese alkaline-earth metal, or ammonium as the electrolyte The anodes so provided are used -in a conventional have Specific advantages in certain uses P a manner in a magnesium primary cell. The advantages greater capacity per unit of volume is generally achieved of employing Suoh an ll are many, but primarily am with less weight. 'One of the primary disad tag s in represented in the decreased delayed action of the cell. ut i ing m gne i a an anode for a P y Cell is The following examples are given to illustrate the that the cells do not always attain full working voltage anodes of the present invention, but are not, to be conimmediately on attempting to reuse them following a rest ed as limitin the invention thereto: "period. This delayed action may vary from 0 to as much as 100 seconds or more depending upon the'specific com- E l 1 position of the components of the cell, the amount of use that has been made of the cell, the intervening resting Two alloy compositions, one of which contains 3 perperiod, and the age of the cell. cent aluminum and 1.0 percent zinc, and 0.2 percent It is a principal object of the present invention to procalcium, the remainder being commercial magnesium vide an anode material which results in a shorter delayed (AZ31A), the second of which contains 3-percent alumiaction when employed in the conventional magnesium num, 1.0 percent zinc, the remainder being magnesium primary cell. Stillanother object of the present inven- (AZ31B) were both treated so as toprovide varying tion is to provide such an anode material which comquantities of indium alloyed therein. Cells containing prises a. conventional magnesium anode having small these alloysas anodes, a cathodeof 91 percent manganese amounts of indium alloyed therein. Another object of the 40 dioxide, 3 percent barium chrom-ate and 6 percent acetylpresent invention is to provide such a magnesium anode ene black, and an electrolyte containing 250 grams per material for primary cells containing from 0.03 to 1.7 liter of magnesium bromide and 0.36 gram per liter of percent indium alloyed therein. Other objects will besodium chromate were employed. Diiferent cells concome apparent hereinafter. rtaining the anodes of the present invention and com- The foregoing and additional objects have been acparison anodes were tested in 2 standard tests: the Railcomplished by providing a magnesium cell containing a road Lantern test utilizing an alternate discharge time magnesium anode, said magnesium anode containing and a rest time of 30 minutes during an 8-hour day with a from 0.03 to 1.7 percent indium alloyed therein. subsequent rest time of 16 hours, 7 days per week, on a Magnesium batteries have been described in a number 32 ohm load for a three cell pack; and, the General of U.S. patents, including Nos. 2,547,907, 2,616,940, Purpose test of 5 minutes per day discharge through 4 2,712,564, etc. These patents all rely on a magnesium ohms per cell, 7 days per week. anode, a cathode into which has been mixed a depolariz- The following table summarizes the results obtained ing agent such as manganese dioxide, an alkaline metal, from these tests:

Delay in Seconds, General Railroad Lantern Purpose Anode Base Alloy Percent Fabricated Eff.

- In State I A.M. P.M. General Max. Ave. Purpose Max. Ave. Max. Ave.

0 4 5.5 4.8 15 11.3 1.5 55.4 .05 3 6.0 4.7 2 1.2 6 2.3 .15 1 6.0 3.2 1 0.1 a 2.4 54 .15 2 6.0 3.9 2 0.6 3 2.2 54 0 2 30 21 42 20 3 1.5 53 .02 3 29 21 2 1.6 2.0 1.4 54 .05 2 32 21 7 2.3 2.0 1.2 53 .12 a 16 12 2 0.1 4.0 1.6 53 .51 3 1s 10 0 0 2 0.9 46 1. as 4 16 1.8 0 0 l (1) As-rolled. (2) As-rolled, annealed 300 C. for }6 hour. (3) As-rolled, annealed 700 C, {or 14 hour. (4) Impact extruded battery cans.

construction were employed in the following tests.

Example A series of D-sized cells having standard steel jacket In Group No. l, the anode was a .025 inch sheet containing 3.5 percent aluminum, 0.24 percent calcium, 0.96 percent zinc, and 0.13 percent indium, the balance being magnesium. The cells from Group 2 containing a similar sheet anode alloyed from 3.1 percent aluminum, 0.17 percent calcium, 0.86 percent zinc, percent indium. These anodes were employed with an electrolyte consisting of 400 grams per liter of magnesium bromide, and 0.36 gram per liter of sodium chromate solution. The cathode mix was 87 percent manganese dioxide, 3 percent barium ch-romate, percent acetylene black and 0.25 percent magnesium powder. It was wet with 440 milliliters of electrolyte per thousand grams of dry material. The weight of the wet cathode mix was 54 grams per cell. These cells were hooked five in a series to make a nine volt pack. Each nine volt pack was employed in an RCA. Transistor Radio 7-B-l0K maintained at a predetermined volume of nine milliamperes and the delay measured by determining the time required to reach this volume. The series of cells were discharged 2 hours per day through 900 ohms to an end voltage of 6 volts. The delay average was determined over this period and the delay was measured at the beginning of the two hour discharge. This test resulted in the following results:

Ave.

Group I 2. 3 Group II 15.0

magnesium having 0.03 to 1.7 percent indium alloy therein.

2. A magnesium battery anode comprising: from 1 to 12 percent aluminum, 0.0 to 3.0 percent zinc, 0.0 to 0.5 percent calcium, 0.03 to 1.7 percent indium, balance magnesium.

3. A magnesium battery anode comprising: from 1 to 12 percent aluminum, 0.0 to 3.0 percent zinc, 0.0 to 0.5 percent calcium, 0.03 to 1.7 percent indium, .less than 0.005 percent iron, less than 0.002 percent nickel, less than 0.6 percent manganese, the balance being magnesium.

4. In a magnesium battery which includes a cathode of manganese dioxide mixed with a carbon, a magnesium anode, a bromide electrolyte, and a carbon current collector, the improvement which comprises: providing said magnesium anode having 0.03 to 1.7 percent indium alloyed therein.

5. In a magnesium battery which includes a cathode of manganese dioxide mixed with carbon, a magnesium anode, a bromide electrolyte, and a carbon current collector, the improvement which comprises: providing an anode which includes from 1 to 12 percent aluminum, 0.0 to 3.0 percent zinc, 0.0 to 0.5 percent calcium, 0.03 to 1.7 percent indium, the balance being magnesium.

6. In a magnesium battery which includes a cathode of manganese dioxide mixed with carbon, 2. magnesium anode, a bromide electrolyte, and a carbon current collector, the improvement which comprises: providing an anode which includes: from 1 to 12 percent aluminum, 0.0 to 3.0 percent zinc, 0.0 to 0.5 percent calcium, 0.03 to 1.7 percent indium, less than 0.005 percent iron, less than 0.002 percent nickel, less than 0.6 percent manganese, the balance being magnesium.

References Cited in the file of this patent UNITED STATES PATENTS 2,683,184 Boswell July 6, 1954 2,836,645 Morehouse et a1. May 27, 1958 FOREIGN PATENTS 1,081,155 France June 9, 1954 

2. A MAGNESIUM BATTERY ANODE COMPRISING: FROM 1 TO 12 PERCENT ALUMINUM, 0.0 TO 3.0 PERCENT ZINC, 0.0 TO 0.5 PERCENT CALCIUM, 0.03 TO 1.7 PERCENT INDIUM, BALANCE MAGNESIUM. 